I am using IAR workbench for building my source. So, gcc option might not work for me.
I verified config.h;
#define MBEDTLS_PLATFORM_MEMORY //is defined
#define MBEDTLS_PLATFORM_FREE_MACRO OS_free
But for calloc, I am giving
#define MBEDTLS_PLATFORM_CALLOC_MACRO(a,b) OS_malloc(a*b)
Still am facing the same.